High density carbon from coal
A high density carbon material produced from coal is described. The carbon material may have a density ranging from about 1.0 g/cc to about 1.6 g/cc and may have a crush strength of up to about 20,000 psi. The high density carbon material is produced by slowly heating comminuted swelling bituminous coal particles under pressures of 400 psi to about 500 psi to a first temperature at about the initial plastic temperature of the coal. The material is held at this temperature for a period of time sufficient to provide for a uniform temperature throughout the coal. The material is then heated to a second temperature for a period of time sufficient to provide for the coal achieving an essentially uniform temperature. The resulting product is a three-dimensional, self-supporting carbon that has a substantially continuous carbon matrix defining grain boundaries within the carbon matrix. The characteristics of the carbon material may be altered by further heating to carbonize or graphitize the high density carbon material.
1. A method for making a carbon material from coal, comprising the steps of:
heating comminuted bituminous coal under pressure to a first temperature of about 300° C. to about 350° C., wherein the pressure ranges from about 400 psig to about 500 psig;
holding at the first temperature for a time sufficient to achieve a substantially uniform temperature throughout the coal, wherein the steps of heating comminuted bituminous coal to the first temperature and holding at the first temperature prevent swelling of the bituminous coal; and
heating to a second temperature of about 480° C. to about 550° C., and at a rate to prevent swelling of the comminuted coal and form a high density carbon material having a density ranging from about 1.0 g/cc to about 1.6 g/cc.
2. The method of claim 1 , wherein the step of heating comminuted bituminous coal under pressure to a first temperature is performed at a rate ranging from about 0.5° C./min to about 2° C./min.
3. The method of claim 1 , wherein the step of heating to a second temperature is performed at a rate ranging from about 0.5° C./min to about 2° C./min.
4. The method of claim 1 , further comprising the step of heating the carbon material to a temperature ranging from about 600° C. to about 1800° C.
5. The method of claim 1 , further comprising the step of heating the carbon material to a temperature greater than about 1800° C.
6. The method of claim 1 , further comprising the step of heating the carbon material to a temperature greater than about 2200° C.
7. The method of claim 1 , further comprising the step of heating the carbon material to a temperature greater than about 2600° C.
8. The method of claim 1 , further comprising the step of heating the carbon material to a temperature ranging from about 1800° C. to about 3200° C.